You for sure have an air pocket so that when the motor gets to running temp the stat opens lets all that cool coolant flow and here comes ole faithful I was a mechanic for 50 years and it happened to me in November in my 66. Your on the right track with an infared temp taker they are super for checking if yo have cold spots on your radiator IE blocked. Hope this helps John BHey all - My 15 year old son and I are working through the mechanics of my his first car, and I am looking for advice on the cooling system.
1966 Coup, A-code, 289 4bbl with AC and power steering. The fan is a six blade, belt driven, 17" diameter, and it sits about 3" away from the 2-row original-looking radiator core.
We live in Phoenix, and since it is currently winter, it is 72 degrees and sunny. We picked up the car about a month ago. It had been sitting in a warehouse in CA for 40 years. Nonetheless, it runs and drives, but we are working through some of the bugs that need to be worked out. The one we are currently working on is that it is overheating. We so far have replaced the temp sending unit (it was completely dead), flushed the block and radiator, installed a 180 deg thermostat (it was missing), replaced the radiator cap (13lb), and replaced the supply, return, and bypass hoses. We spent considerable time trying to make sure we purged the air out of the system after the flush, but I will be honest, I am only about 80% sure we got it all.
When we start the car from cold, it will run and idle for about 15 minutes before the temp gauge goes to about center. As I watch with the radiator cap off, I can see some flowing coolant after a while, but then there is an event point where it just guysers out of the cap. Probably 4-6" of fountain coming out of the fill hole. If I leave the cap on, the gauge will float up to about 80% to H, and then start coming back down to about 60%, then swing up to 85%, back to 65%... it kind of ratchets its way up to the top end of the gauge and then I shut it down. At that point, coolant is streaming out of the pressure relief hose.
A couple of things I figured out by reading through many of the posts... first - it does not have a fan shroud, and that appears to be a pretty big deal. So I went ahead and ordered one that is close to stock.
Second - I learned that taking temps with the ol' IR gun could prove handy, so we will be doing that part tomorrow. I plan to take reads at the thermostat housing, supply hose and return hose. I am hoping to figure out whether or not the radiator is actually removing any heat. Then I will do it again with the fan shroud on to see if I have any improvement. I will also use this data to see if the sending unit/gauge is reading correctly.
So here are my questions:
1) is it normal to get a guyser out of the radiator?
2) Are there any other points that I should be reading temperature?
3) I am pretty suspicious of the radiator being plugged up after sitting for 40 years, so assuming I need to replace it, should I go with a 2, 3, or 4 row? Does anyone have a specific recommendation for a Phoenix based car?
4) Knowing it will be blazing hot in a few months, and the car has Air Conditioning, should I plan to install an electric fan?
Thanks in advance for your insight!